A question was posted over on Bob The Oil Guy regarding battery desulfators and whether or not they work. There were some interesting answers, much opinion and some real life examples of people using these devices. User 3311 must be a battery sales man as his response said "No they don't work. Electrical snake oil..." I would suggest the opposite is true.
User 3311 had a simplistic, but theoretically correct statement, in that the double sulfate chemical reaction occurring in lead acid batteries has two sides to the equation. During discharge non-crystalline sulfate matter is left on the plates and during charging this material is mostly transformed back to the starting compounds of lead, lead dioxide, and sulfuric acid (see a detail explanation of this on our FAQ questions: What is Sulfation?). However, it is not a perfect world and inevitably something will go wrong. Batteries left in a discharged state too long will see the non-crystalline sulfate matter harden into a crystalline form. Normal charging will no longer be able reverse this effect. Even batteries left on a trickle or float charge can eventually show a sign of sulfation as the process is not perfect and some material will not get converted back. Sad, but true. This is why sulfation is the #1 killer of lead acid batteries and why battery desulfators are sorely needed.
Back in the day, before the invention of AGM batteries, charger manufacturers would increase the voltage of the battery to try and break down the hardened crystals. This boiling effect would slough off some of the crystals as well as part of the active material on the plates. It would all end up in the bottom of the battery to slush around and cause problems in the future. The immediate effect would be noticeable, but the lasting damage would ultimately shorten the life of the battery. This method would have little or no effect on AGM batteries due to the tight weave of the fibrous matt. Battery desulfators come attack the issue in a different way.
PulseTech to the Rescue!
A few years back Pulse Tech patented a pulse frequency that would dissolve the crystalized sulfate and return it to its original form. And with that the first Battery Desulfator was born! The military was (and is) its primary customer. Their pulse frequency is a range from 22-28 KHz. That is roughly 22,000-28,000 pulses per second. The years of testing has produced empirical data that shows the effect on lead plates and validates their use as a battery desulfator.
The Technology behind Battery Desulfators
First let me dispel the differences between pulse charging and frequency charging which are often lumped together and used interchangeably. Pulse charging uses a burst of high voltage within the charge cycle as its primary tool to dislodge or shock the crystals into surrendering. Some of these pulses, though measured in micro-seconds, can reach as high as 60 volts! High frequency pulsing maintains low or traditional voltage ranges and adjusts the wave and amplitude according to the manufacturers specifications. Both techniques can be used congruently. Battery desulfators can be used on all types of lead acid batteries including AGM and Gel. [SIDE NOTE Do not use a pulsing charger on a lithium battery. These batteries have a built in battery management system (BMS) and are chemically different. A non-pulsing lead acid type charger can be used on a similar voltage lithium battery.]
There are 4 basic wave forms used. The original one is named after the patent holder and is called the PulseTech Pulse Waveform. This microprocessor controlled pulse rapidly rises in less than one microsecond to its maximum amplitude and gradually returns to zero. There is no abrupt stop, no battery drain and is controlled via a separate circuit independent of the charging circuit. Battery Minder uses a similar hybrid waveform where they combine moderately high voltage pulses with their short duty cycle.
The Sine Wave version fluctuates gradually between positive and negative charge. This pulse is much "softer" than the others and may have limited effect on the sulfate crystals. The upper voltage range must be carefully controlled to prevent overcharging and gassing.
The remaining two wave forms are the Square Wave and Negative Pulse Wave. The square wave is used by Battery Life Saver and by its design dwells longer in the maximum voltage range before abruptly returning to zero. The negative wave is the mirror image of the square wave but has the added concern that the charge is restricted during the down cycle of the pulse.
Players In The Market
Today, there are several companies offering some form of battery desulfator. They each approach the science a little differently and each claim theirs is the best. BatteryMinder is the next best known, after PulseTech and they use a sine wave pulse form. Like Pulse Tech, they have a broad range of desulphating chargers, solar panels and on-board units. Battery Life Saver makes on-board "battery rejuvenators" as they call them, which utilize a variant known as the square wave pulse. WizBangPlus is a smaller player in the market that uses frequency pulsing in the range of 0.8 - 1.2 KHz. We have never used or tested one of the WizBang units and do not know what type of waveform they use (i.e. sine wave, square wave, negative pulse wave, etc.).
Some people, in the forum post that prompted this article, suggested users should use a CTEK 3300 to satisfy their sulphation needs. We do not think the CTEK charger lives up to its claim and feel it should be avoided if desulfation is your goal. In fact several years ago [November 2010] when we noticed batteries did not seem to respond, we contacted Borje the president of CTEK and he agreed to purchase a XC100-P Pulse Tech charger to do a comparative analysis. After some dialogue we never heard back from Borje or CTEK and frankly got the cold shoulder. To us this suggested our results were validated and their product was indeed inferior. Otherwise we would have expected a report showing how they outshine the competition.
We Know Battery Desulfators Work!
I personally would avoid high voltage pulsers and stick to the frequency based battery desulfators. Putting up to 60V into a 12V battery, even if for only a fraction of a second, just does not sound like it will produce the best long term effect. There is merit to the combination of moderately high voltage pulses combined with a frequency pulsing that Battery Minder uses. Our testing of their products is not as extensive as with the PulseTech battery desulfators.
We have posted previously, stories of our own staff testing and using the Pulse Tech XC100-P charger. (Click here to read Chris's experience). We know first-hand battery desulfators work. As to which company has the best technology we will leave that decision up to you. Hearing your experiences with these devices and opinions that come from testing them are welcome. Please feel free to share your desulfation story and help make a believer of those who say it is nothing but snake oil.
For a full listing of the battery desulfation products offered by Impact Battery see our website http://www.impactbattery.com/battery-desulfators/